The use of compositions based on ethylene homopolymer or copolymers in the manufacture of stretch wrap films having good cling and optical properties is known, e.g., as shown in U.S. Pat. Nos. 4,073,782 and 4,222,913. U.S. Pat. No. 4,073,782 discloses stretch wrap films made from a ternary composition wherein the resin component is a polyethylene of any suitable density, a copolymer of ethylene and vinyl acetate, or a mixture of the above mentioned polyethylene and copolymer. The remaining essential components of the ternary composition are sorbitan monooleate, which is mainly added as an antihazing agent, and a liquid paraffin, as an adhesiveness modifier. When polyethylene is chosen as the resin component, the sorbitan monooleate concentration should range between about 0.5 to 2.0% based on the polyethylene weight. The liquid paraffin concentration should fall in the range of 0.5 to 6% of the polymer. If no liquid paraffin is used, a film produced from the resulting binary composition is exceedingly sticky and cannot be used as wrapping material. Although the films produced in accordance with the teachings of the aforementioned patent perform very well in most applications, their strength and toughness properties are somewhat inferior for use in stretch wrapping of pallet loads. U.S. Pat. No. 4,222,913 discloses improvement in these properties by the use of a resin which is a blend of ethylene-vinyl acetate copolymer with a copolymer of propylene and small amounts of ethylene.
The recently developed linear low density polyethylenes have the desired strength and toughness properties required for stretch wrap applications, but do not possess the required cling, which in the case of conventional polyethylene, can at least be partially obtained by incorporation of vinyl acetate as a comonomer.
It is, therefore, an object of the present invention to provide a composition from which films can be prepared having improved strength, toughness and cling properties.
It is another object to provide a composition suitable for manufacture of pallet wrap stretch films of superior cling quality which will function at both ambient and winter warehouse temperatures.
A further object is to provide stretch wrap films of improved properties. Other objects will become apparent from a reading of the specification and appended claims.